Abstract (30 lines max) Medical and nonmedical use of prescription opioids has rocketed in the US over the past two decades. The rise in opioid use during pregnancy marked disparities among AI/AN women and newborns. While there are evidence-based treatment strategies recommended for use during pregnancy and in the postnatal use period, use of these strategies is substantially lower in AI/AN across the US. As sovereign nations, tribes are often responsible for policies, practices, and infrastructure improvements to address these problems. The Northwest Tribal Epidemiology Center (The EpiCenter) is tasked with responding to the data needs of the 43 NW Tribes, including Opioid use, Neonatal Abstinence Syndrome (NAS) and access and utilization of treatment related information. We initiate this proposal in response to these requests and needs of the tribes. We plan to perform an epidemiologic assessment to determine the magnitude and impact of maternal substance use during pregnancy and NAS among American Indians in the Northwest. We will leverage ongoing and planned work in the Tribal Epidemiology Center to estimate race- corrected rates and trends of maternal substance use during pregnancy and NAS in hospital discharge data. We will also investigate opioid use and treatment in the NW as reported in Indian Health Service?s national data repository. We will complement these quantitative data with qualitative data to help us understand the environmental, social and organizational structures, processes, and policies, as well as individual behaviors that influence access to, or use of, treatment in Northwest Tribes This proposal will bring together epidemiologic and content experts, as advisory board members to respond to the data and ensure that analyses and reports are useful to decision-makers in various capacities. Upon successful completion of these study aims proposed, we will be poised to implement and evaluate future tribal interventions and policies, which in the long term could reduce the effect of the opioid crisis in Northwest American Indian communities.